In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
NFS: fix delegation_hash_table leak when nfs4_server_common_setup() fails<\/p>\n
nfs4_server_common_setup() allocates server->delegation_hash_table
\nfirst, but server->destroy – the only path that frees the table via
\nnfs4_destroy_server() – is not assigned until the very end of the
\nfunction. If any intermediate step fails (the is_ds_only_client()
\ncheck, nfs4_init_session(), nfs4_get_rootfh(), or nfs_probe_server()),
\nthe function returns with server->destroy still NULL, so the caller’s
\nnfs_free_server() skips the destroy callback and the hash table is
\nleaked (4 KiB per attempt with the default delegation watermark).<\/p>\n
This is trivially reachable from userspace: every failed NFSv4 mount
\nleaks one allocation. A client that persistently retries a mount that
\ncannot succeed leaks kernel memory without bound. Observed in
\nproduction where a Longhorn backup poller retried mount.nfs4 against
\nan NFSv3-only server roughly 10 times per second, leaking ~3.4 GiB of
\nunreclaimable slab (kmalloc-rnd-13-4k) per day; the node accumulated
\n12 GiB of leaked slab before the source was identified via the
\nkmem:kmalloc tracepoint (call_site=nfs4_delegation_hash_alloc).<\/p>\n
Reproducer:<\/p>\n
# server exports NFSv3 only (or export path absent for v4)
\n while :; do mount -t nfs4 :\/missing \/mnt; done
\n # watch SUnreclaim in \/proc\/meminfo grow 4 KiB per iteration<\/p>\n
Free the table on the error paths between the allocation and the
\nassignment of server->destroy.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
NFS: fix delegation_hash_table leak when nfs4_server_common_setup() fails<\/p>\n
nfs4_server_common_setup() allocates server->delegation_<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-21636","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/21636","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=21636"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=21636"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=21636"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}